Erlang SNS amazon erlcloud publish fails with timeout error - amazon-web-services

Question

I am trying to use erlcloud to send push notification to mobile based on endpointArn which received from client. I am able to successfully push notification with Java application. But same stuff if I try with erlang, it is giving timeout error. Below are code samples.
Config = erlcloud_sns:new(<<"Access Key">>,<<"secret Key">>,<<"sns.us-west-2.amazonaws.com">>).
erlcloud_sns:publish(target,<<"arn:aws:sns:us-west-2:2315XXXXXX:endpoint/GCM/testapp/XXXXXXX-fe9a-304e-aa52-XXXXXXXX">>,<<"ok">>,undefined,[],Config).
Last statement is showing below error.
** exception error: {sns_error,{socket_error,timeout}}
in function erlcloud_sns:sns_xml_request/3 (src/erlcloud_sns.erl, line 670)
in call from erlcloud_sns:publish/6 (src/erlcloud_sns.erl, line 471)
Same value of access_key, secret_key, Host and endpointArn works from Java program.

Answer 1

Short answer
Change your parameters to strings and it will work. i.e:
Config = erlcloud_sns:new("Access Key","secret Key","sns.us-west-2.amazonaws.com").
erlcloud_sns:publish(target,"arn:aws:sns:us-west-2:2315XXXXXX:endpoint/GCM/testapp/XXXXXXX-fe9a-304e-aa52-XXXXXXXX","ok",undefined,[],Config).
Long answer
erlcloud expects strings for all parameters. Unfortunately, instead of validating config values before storing them, it stores whatever you provide then fails on trying to use it. In this case, it can't recognise the credentials here (because the guard function is_list returns false). In the end, it falls back to getting credentials from ECS (here), hitting a timeout there and resulting in the error you see.